JPS6312944A - Inspection instrument for failure of packaging parts - Google Patents

Abstract

PURPOSE:To shorten an inspection time by accumulating the number of times of an inspection and the number of times of a defect of each parts whenever the inspection is executed, calculating a defect generation rate from said number of times of an inspection and the number of times of a defect, and executing a failure inspection of each parts in accordance with a result of its calculation. CONSTITUTION:At the time of inspecting whether a defect exists or not, with regard to packaging parts 2 on a measuring table 1, the number of times of an inspection against each parts and the number of times of a defect by which it is decided that a defect exists are accumulated in advance in a memory 9. Subsequently, by an arithmetic operation control device 7, a defect generation rate is calculated by the number of times of inspection and the number of times of defect, and in accordance with a result of its calculation, the inspection frequency of each parts is derived, and also, updated. When this inspection frequency is determined, an inspection of parts is executed by the frequency corresponding thereto. That is to say, as for parts whose defect generation rate is low, the number of times of inspection is decreased, and as for parts whose defect generation rate is high, the number of times of inspection is increased, by which the inspection is executed efficiently, and the inspection time is shortened.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention is used to inspect the quality of each component mounted on a printed wiring board (hereinafter simply referred to as "board"). In relation to inspection equipment, the present invention particularly relates to miniaturized electronic components without leads (this is referred to as "
The present invention relates to a defect inspection device for mounted components suitable for this type of inspection of "surface mounted components".

<Prior Art> In recent years, various electronic components have become significantly smaller, and many surface-mounted components without leads have come into use.

Conventionally, in order to mount this type of component on a board, Figure 8 (1)
As shown in ~(4), first, cream solder 22 is applied corresponding to the component mounting position on the board 21 (Fig. 8 (1)).
1), grab the component 23 to be mounted using a chip mounter (not shown), position and place it on the board 21,
This component 23 is soldered so that the electrode 24 is in contact with the cream solder 22 (see FIG. 8(2)).

When the same work is completed for all the parts, the sheet 21 is placed on the conveyor 25 and passed through the reflow oven, and the cream solder 22 is melted with an infrared lamp 26 (see Fig. 8 (31)). Then, the board 21 is led out of the furnace and the molten solder is cooled and solidified (see FIG. 8 (4)).

In the above component mounting process, not all components 23 are necessarily mounted properly on the board 21, and some components may not be mounted at the specified positions on the board 21, or the mounted components may not be located at the specified positions. There may be misalignment or components may not be properly soldered onto the board.

9 [1 (1) to (4) show the mechanism by which defective solder joints of components occur, and FIG. Indicates a closed state. Next, this board 21 is passed through a reflow oven for soldering treatment, but in the preheating stage of FIG. Upon activation, the solvent evaporates and a gas layer is generated on the surface of the cream solder 22. Although the cream solder 22 is semi-molten in the heating stage shown in FIG. Interveningly, part 23
is in a state where it can be easily separated from the substrate 21. 9th
In Figure (4), the cream solder 22 is completely melted at part B in the other soldering process, and the surface tension generated when it solidifies pulls the component 23.
Make it stand out more. Therefore, in this state, the electrode 24 of the soldered component 23 is not in contact with the board 21.

After the soldering process described above is completed and the component mounting process is completed, the board with the components mounted is sent to an inspection process to detect missing components from the board.

The presence or absence of defects such as misalignment of components from specified positions and poor solder bonding of components to the board is inspected.

Conventionally, this type of inspection work has generally been carried out by an inspector picking up a component-mounted board and observing it from all sides using a magnifying lens.

Furthermore, in recent years, an automatic inspection device has been proposed for soldering using transmitted X-rays, and by introducing this device into the inspection line, inspections are being streamlined. This automatic inspection device focuses on the fact that solder contains a lead component that transmits X-rays, and irradiates the component mounting board with 1) and generates an image according to the amount of radiation transmitted. This image is used to inspect component mounting defects.

In any of the above-mentioned inspection methods, when a component-mounted board is sent to the inspection process, the actual situation is that all the components mounted on the board are uniformly subjected to the necessary inspections.

<Problems to be Solved by the Invention> However, according to the inventor's observation, defects such as missing parts, misalignment of parts, defective solder joints, etc. that appear on parts mounted on the board are common to all parts on the board. Defects do not occur with the same probability, and the defect occurrence rate differs for each component. Possible causes of this include differences in component mounting density around the parts where the components are located, variations in the amount of cream solder applied, and uneven stability of the chip mounter with respect to the placement position of one component bag.

Therefore, in the past, even parts with an extremely low defect rate were inspected at the same frequency as parts with a high defect rate, resulting in a lot of wasted inspection and poor inspection efficiency.

In view of the above-mentioned circumstances, the present invention provides a new defect inspection device for mounted components that improves inspection efficiency and shortens inspection time by inspecting mounted components at an inspection frequency that corresponds to the defect occurrence rate. The purpose is to

<Means for Solving the Problems> The structure of the present invention for achieving the above object will be explained using FIGS. 1 to 6 corresponding to one embodiment. In an apparatus for inspecting a plurality of mounted components 5 for mounting defects, a storage means (417) for accumulating and recording the number of times each component 5 has been inspected and the number of times it has been determined that there is a defect each time it is inspected; (corresponds to the memory 9 in the illustrated example), and an arithmetic control means (corresponding to the memory 9 in the illustrated example) that calculates the defect occurrence rate from the number of inspections and the number of defects, and determines and updates the inspection frequency of each component 5 according to the calculation result. (corresponding to the illustrated arithmetic and control device 7 and memory bag W8); and inspection execution means (corresponding to the illustrated example of the camera 3, the light projector 4, and the arithmetic and control device) that inspect mounting defects of each component 5 according to the inspection frequency. 7) and gu (true).

<Operation> When each mounted component 5 on the board 9 is inspected for defects, the number of times each component has been inspected and the number of defects determined to be defective are stored in the memory 9 each time.

Then, the arithmetic and control unit 7 calculates the defect occurrence rate from the current number of inspections and the number of defects, and depending on the calculation result,
The inspection frequency will be determined and updated.

Once the inspection severity is determined, the component is inspected at a frequency corresponding to the inspection severity. For example, parts with a low defect rate are inspected from time to time, and parts with a high defect rate are frequently inspected, which allows for efficient inspection.

<Embodiment> FIG. 1 shows a defect inspection device for mounted components according to an embodiment of the present invention.

The illustrated apparatus is for inspecting whether or not there is any floating of parts at the solder joints of a plurality of surface-mounted parts mounted on a board, but the present invention is not limited to this. This method can also be applied to inspecting components other than surface-mounted components, and can also be applied to inspecting defects other than solder joint defects.

In the illustrated example, a measurement table 1 consisting of an XY stage
The inspection target 2 (components mounted on the board) is shown above.
A camera 3 consisting of an image sensor and a light projecting device 4 using a semiconductor laser as a light source are disposed above the camera 3.

As shown in FIGS. 2 and 3, this light projecting device 4 irradiates a plate-shaped light diagonally downward onto a mounted component 5 on a board 9 to be inspected, and illuminates the solder joints on the side surface of the component 5. 100
The purpose is to generate a light section line 6 where plate-like lights intersect on the surface, and the camera 3 images the light section line 6 at an obliquely upward position to generate a ray image of the light section line 6. belongs to.

Above camera 3. The light projection device 4 and the measurement table 1 are connected to an arithmetic control device 7 consisting of a microcomputer CF'tJ, and this arithmetic control device 7 controls the imaging operation of the camera 3, the light projection operation of the light projection device 40, The movement of the measurement table 1 and the like are controlled in a series by control signals, and a video signal is taken in from the camera 3, necessary image processing is performed, and a light beam image of the light cutting line 6 is displayed on a monitor television 8.

In order to inspect the solder joint 10 of a component using this device example, first, the calculation side '4'B device 7 moves the measurement table 1 and places the camera 3 and the light projecting device 4 at the prescribed mounting position of the inspection component 5. Place it in the corresponding position. Next, when an operation command is given to the camera 3 and the light projection device 4 from the arithmetic control device 7, the light projection device 4 starts the light projection operation, and a plate-shaped light is directed toward the solder joint 10 of the inspection component 5. irradiated.

This plate-shaped light is not only on the surface of the solder joint 10 but also on the surface of the solder joint 10.
The beam is irradiated over a range from the surface of the component 5 to the surface of the substrate 9, and a series of light cutting lines 6 where the plate-shaped lights intersect are generated as shown in FIGS. 2 and 3. This light section line 6 is imaged by the camera 3 located diagonally above the light section line 6 to generate a ray image of the light section line 6, and the video signal is taken into the arithmetic and control unit 7, where necessary image processing is performed. displayed on the monitor television 8.

FIG. 4 shows a light beam image of the light cutting line displayed on the monitor television 8. If the solder joint part of the component 0 is in a proper state and no lifting occurs on the component 5, the 4th As shown in FIG. 1, the optical cutting IfrvA6a on the surface of the component 5 and the optical cutting Ni6C on the surface of the substrate 9 are continuous via the optical cutting line 6b on the surface of the solder joint 10.

On the other hand, if the solder joint 8510 of the component is defective and the component 5 is floating above the board 9, as shown in FIG. A break X will occur between the cutting line 6a, and therefore, by checking the presence or absence of this break X, floating of the component can be easily discovered.

Returning to FIG. 1, each time the above-mentioned inspection is performed on each component 5 on the board 9, the arithmetic and control unit 7 stores in its memory the number of times the component has been inspected and the number of times it has been determined that there is a defect. After calculating the defect occurrence rate of the part from the accumulated number of inspections and the number of defects, the inspection frequency of the part is calculated by referring to a table stored in advance in the memory 9. Search and update.

FIG. 5 shows the number of inspections and the number of defects for each component stored in the memory 9. In the same figure, n, , n, L, n
l---. is the part number, 2. The number of inspections for each part No. 3, and f.

f, , f3, . . . respectively indicate the number of defects.

Therefore, for example, a part with part number 1 has a number of inspections of nl.
, it can be seen that the number of defects is f.

FIG. 6 shows a conversion table T between defect occurrence rate and inspection frequency, which is stored in advance in the same memory 9, and in the figure, el, ez, el.

..., e, l (However, OS el < e2 <
el<0. ...kuea, ea = 1> is the defect occurrence rate, and P, ・P2・Py, ・・P7 (
However, O≦p, <pz< p, <...<Pf,,
However, P, , = 1 or P, , <1> indicates the inspection frequency corresponding to each defect occurrence rate.

FIGS. 7 and 8 show a first step in determining the frequency of inspection.

First, in step 1 in the figure (indicated by rSTIJ in the figure), each component 5 mounted on the board 9 is inspected at a frequency of 100%.
(inspection every time), and each time each part is inspected, 1 is added to the ``number of inspections'' in the memory 9, and 1 is added to the ``number of defects'' each time it is determined that there is a defect. , the test results are stored in memory 9 (step 2).

This data accumulation process is repeatedly executed until the amount of accumulated data (the number of inspections) reaches a predetermined threshold, and the determination of "Has a certain amount been accumulated?" in step 3 is "YES".
S'', the calculation 2.1rJ device 7 calculates the defect occurrence rate α of the part by calculating the following formula 0 from the current number of inspections n and the current number of defects f. (Step 7 B4).

α,=f,/ni...■Next, the arithmetic and control unit 7 refers to the conversion table T stored in the memory 9 for the calculated defect incidence rate α, and determines the inspection frequency p of the component.

is calculated and updated (step 5).

FIG. 8 shows the control procedure of the arithmetic and control unit 7 for determining this inspection frequency p.
1, the arithmetic and control unit 7 initializes the internal counter j (j=1)'.

Then, specify the start address of the conversion table T. Next, the arithmetic and control unit 7 reads the defect occurrence rate e set at that address, and compares this with the defect incidence rate αi calculated above (step 12).

Assuming that the defect occurrence rate α1 currently being calculated is the closest value to the j-th (just j≠1) defect occurrence rate e in the conversion table T, and that αi≦02, the determination in step 12 is If the answer is "NO", the counter j is incremented by 1 in step 13, and the same determination as in step 12 is made.

As a result of this iterative processing, the determination in step 12 is YES.”
When , the process proceeds to step 14, where the j-th data PJ in the conversion table T is read out, and the inspection frequency of that part is determined to be P.

1. The procedure for determining the inspection frequency described above is performed for each component on the board, and once the inspection frequency for that component is determined, the next inspection for that component is performed based on the determined inspection frequency. That will happen.

<Effects of the Invention> As described above, this invention accumulates the number of inspections and the number of defects for each component each time it is inspected, calculates the defect occurrence rate from the number of inspections and the number of defects, and calculates the defect occurrence rate according to the calculation result. In addition to determining the inspection frequency for each part, the defect inspection method for each part is carried out according to this inspection frequency, so parts with a low defect incidence rate can be inspected using a sampling inspection method with a low inspection frequency. For parts with a high occurrence rate, an inspection method that is similar to every-time inspection is carried out, which reduces waste in inspections, improves inspection efficiency, and shortens inspection time. It has achieved remarkable effects.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a defect inspection device for mounted components according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the positional relationship between a camera and a light projector, and Fig. 3 is a mounted part showing a solder joint. 4 is an explanatory diagram showing a ray image of a light section line,
FIG. 5 and FIG. 6 are explanatory diagrams showing the storage contents of the memory;
Figures 7 and 8 are flowcharts showing the procedure for determining the inspection frequency, Figure 9 is a cross-sectional view showing the procedure for mounting components on a board, and Figure 10 is a cross-sectional view showing the mechanism of occurrence of defective solder joints of components. It is. 3...Camera 4...Light emitter 7...Arithmetic control device 9...Memory

Claims (3)

[Claims] (1) In a device that inspects multiple components mounted on a board for mounting defects, the number of times each component was inspected and the number of times it was determined that there was a defect are accumulated and stored for each inspection. a storage means; an arithmetic control means for calculating the defect occurrence rate from the number of inspections and the number of defects; and determining and updating the frequency of inspection of each part according to the calculation result; 1. A defective inspection device for a mounted component, comprising: inspection execution means for inspecting for a defective mounting. (2) The device for inspecting defects in mounted components according to claim 1, wherein the component is a surface-mounted component. (3) The inspection execution means includes a light projecting device for irradiating a plate-shaped light onto the solder joint between the board and the component to generate a light cutting line on the surface thereof, and an image capturing device for capturing an image of the light cutting line. 2. A defect inspection device for mounted components according to claim 1, comprising a camera for generating a light beam image, and an arithmetic control device for executing predetermined arithmetic processing related to inspection for defective mounting of the component based on the light beam image.